Collators have evolved for use with automatic sheet reproducing machines, wherein the collated set of sheets are stapled or finished in the collator trays.
The problems of stapling in combination with collating sets of sheets differ, depending upon the nature of the collator. For example, when the collating trays are disposed in fixed stacks, spaced vertically to receive a selected number of sheets in sets in the trays, it is a relatively simple task to mechanically remove sets of sheets from the trays and transport the sheets to a stapling station or finishing station or to move the trays from a sheet receiving position to a sheet stapling or finishing position at which the sets are bound.
In recent years, collating or sheet sorting machines have been developed for use in conjunction with reproducing machines i.e., photocopying, or printing machines, wherein the collators or sorters are of a compact configuration, having trays which are mounted so as to be shifted from positions above and below a sheet entry location at which sheets are fed from the reproducing machine, or at the discharge location of a sheet transport, at which the trays are spaced relatively far apart to facilitate entry of a desired number of sheets. At the positions above and below the sheet entry location, the trays may be close together and can compact the sheets into a reasonably tight set.
These moving bin sorters or collators provide limited space for the purpose of installing a stapler and the closely spaced relationship of the trays, in all but the sheet receiving position renders difficult application to the structure of an automatic stapler for in-tray stapling of the sets.
Prior devices have been developed, however, for in-tray stapling of collated sets, in a number of ways. Typical moving tray sorters have the trays extended upwardly on an incline in the direction of sheet movement into the trays and the trays are actuated by a suitable cam to vertically move the ends of the trays proximate the sheet entry from below the sheet entry to above the sheet entry.
U.S. Pat. No. 4,928,941, granted May 29, 1991, to Nobutaka Uto, et al discloses one example of a sorter combined with a stapler which is moved from a position out of the path of sheets entering a tray to position at which the anvil of the stapler is moved to a position below the set of sheets and the stapler body occupies space caused by the inherent longitudinal displacement of the trays above the sheet receiving tray, as the inclined tray moves from below to above the sheet entry location. The longitudinal displacement of the superposed trays provides space for the stapler body, even through the trays are not sufficiently vertically spaced to provide space for the stapler body.
U.S. Pat. Nos. 4,687,191, granted Aug. 18, 1987, to Stemmle and 4,681,310, granted Jul. 21, 1987 to Cooper, disclose moving tray sorters of the type wherein the trays are spaced apart to receive sheets and are close together above and below the sheet entry location. In these prior devices, the tray shifting or indexing means are constructed to cause the trays to provide a space or spaces in addition to the normal sheet receiving spacing of the trays, whereby the stapler may be moved from a position clearing the paper path at the sheet inlet to a position at which the anvil and body of the stapler are accommodated by the additional spaces between trays.
On the other hand, the need for providing space for the stapler may be obviated in the case that the tray may be shifted to the stapler. As indicated above, the mode of operation can be accomplished simply in vertically spaced and fixed trays which can be translated horizontally to or from a stapler. Also, it is known to use certain tray shifting mechanisms, including guides which direct the course of the tray ends proximate the sheet inlet location, so that the trays are moved horizontally opposite to the direction of sheet travel into the stapler throat between the anvil and the body of a fixed stapler which is not restrained in its application to a set of sheets by the path of sheets into the trays during normal sorting or collating of the sheets.
In all of these set stapling or binding operations, there is a problem of stapling efficiency if the set of sheets is not in a compact and neat order during staple penetration when the stapler is activated. Transfer devices which grip the set of sheets, transfer the set to an out of the way stapler and return the stapled sets to the tray or deposit the sets in a receptacle are quite efficient due to the clamping action of the transfer device on the sets. Such a finisher is shown in Noto U.S. Pat. No. 4,361,393. However, such machines, usually referred to as finishers, either in association with a collator on a reproduction machine or used for off-line collating, are large and expensive, and do not lend themselves to advantageous use in conjunction with typical, small compact sorters used in combination with photocopying machines, such as the sorter disclosed in my U.S. Pat. No. 4,911,424, granted Apr. 13, 1985, or other compact sorters such as that shown in my prior U.S. Pat. No. 4,343,463, granted Aug. 10, 1982, as examples of such sorters, with which the present invention is concerned.
Stapling devices which are mounted at one side of the trays of the sorter are also known, as disclosed in Morii et al, U.S. Pat. No. 4,971,302, but such a construction results in increased overall width of the machine and hinders access to the stapled sets or unstapled copies at the stapling side of the sorter.